Killing of Caenorhabditis elegans by Pseudomonas aeruginosa used to model mammalian bacterial pathogenesis

We show that a single clinical isolate of the human opportunistic pathogen Pseudomonas aeruginosa (strain PA14),which previously was shown to be patho genic in mice and plants, also kills Caenorhabditis elegans, The rate of PA 14-mediated killing of C. elegans depends on the composition of the agar me dium on which PA14 is grown. When PA14 is grown on minimal medium, killing occurs over the course of several days and is referred to as "slow" killing . When PA14 is groan on high-osmolarity medium, killing occurs over the cou rse of several hours and is referred to as "fast" killing. Several lines of evidence, including the fact that heat-killed bacteria are still capable o f fast but not slow killing of C. elegans, indicate that fast and slow kill ing occur by distinct mechanisms, Slow killing involves an infection-like p rocess and correlates with the accumulation of PA14 within worm intestines. Among 10 PA14 virulence-related mutants that had been shown previously to affect pathogenicity in plants and mice, 6 were less effective in killing C . elegans under both fast- and slow-killing conditions, indicating a high d egree of commonalty among the P, aeruginosa factors required for pathogenic ity in disparate eukaryotic hosts, Thus, we show that a C. elegans pathogen icity model that is genetically tractable from the perspectives of both hos t and pathogen can be used to model mammalian bacterial pathogenesis.